1. Field of the Invention
This invention relates to an opening/closing device for tail gate in the dump truck which is installed at the rear part of the carrier section thereof.
2. Description of the Prior Art
In a conventional type of dump truck in which a tail gate is opened by inclining the carrier section with a dump mechanism so as to discharge or dump the material to be transported such as sand, soil and gravel etc., the opening/closing device for the tail gate is a simple structure, as shown in FIGS. 12 and 13, where the arm (14) of the tail gate (13) is pivotally attached, by an axis (15), to the bracket (12) fixed to the upper ends of both side walls of the burden carrier (11). Thus, usually the tail gate (13) may be rotated rearwardly around a fulcrum point of the axis (15). However, in case of loading of sand and soil etc. higher than that of the tail gate (13), or in case of performing a fast inclination of the burden carrier (11), the upper part of the tail gate (13) is applied with a heavy load from the sliding soil and sand etc., so that it becomes difficult to rotate the tail gate (13) around the axis (15). Therefore, the sand and soil etc. are dropped down over the tail gate (13), the tail gate (13) is buried completely by the sand and soil etc., so that it sometimes occured that the dump truck may not be moved forward. Transmitting of the center of gravity of the dump truck is directed in a rearward direction when the sand and soil are discharged, thereby the front wheels of the dump truck are lifted up to cause a dangerous condition.
Further, in case of a conventional type of the opening/closing device for the tail gate, an opening of the tail gate is narrow, so that if the sand and soil contain a relatively large sized rock therein, they may not be discharged frequently unless the tail gate is removed therefrom, resulting in making a substantially less efficient operation. Narrow opening of the tail gate may not enable a high discharging or unloading of the sand and soil etc. in a narrow place, so that the conventional type of the dump truck shows such a disadvantage as requiring a little wider storing or accumulating place.
In reference to the above disadvantage, the conventional type of the system is made such that the bracket (12) is made high and the tail gate arm (14) is also extended. However, if the bracket (12) is made high, some dangerous conditions are found in which it is struck against the bucket of the power shovel etc. during a loading operation of the sand and soil etc. And extension of the arm (14) of the tail gate is apt to cause it to be easily broken and at the same time it shows such a disadvantage as the tail gate may not be operated smoothly when the material to be transported is discharged.